Apparatus for casting ingots



May 26, 1970 KAZURO SUZUKI ET AL APPARATUS FOR CASTING INGOTS Filed July19, 1966 o on o 4 Sheets-Sheet 1 F/g-Z IIW ,2 /6 3 Z f5 Q INVENTORS.KAzuRo suzuum BY HWOSH' VAHAQKA Aw KM A GEMT May 26, 1970 KAZURO SUZUKIET AL 3,513,903

APPARATUS FOR CASTING INGOTS Filed July 19, 1966 4 Sheets-Sheet 2HHHHQWHHHH INVENTORS. KAz uuQO suquuu BY SH YA HHOl-(A Aeeur May 26,1970 Filed July 19. 1966 FIG.?

KAZURO SUZUKI L APPARATUS FOR CASTING INGOTS 4 Sheets-Sheet 5 IMV6NTOR3,KAZlLRO SLLZLLKI HlROSHl VRHADKQ a KW KM Aaeuf May 26, 1970 KAZUROSUZUKI ET AL 3,513,903

APPARATUS FOR CASTING INGOTS Filed July 19, 1966 4 Sheets-Sheet 4AVERAGE MAXIMUM ROUGHNESS I32# ROUGHNESS AVERAGE MAXIMUM ROUGHNESS 33pINVENTORS. KAZuQO sumuu BY HIROSH' YAHAOKA United States Patent3,513,903- APPARATUS FOR CASTING INGOTS Kazuro Suzuki and HiroshiYamaoka, Osaka-fu, Japan, assignors to Sumitomo Metal Industries, Ltd.,Osaka,

Japan Filed July 19, 1966, Ser. No. 566,296 Claims priority, applicationJapan, July 21, 1965, 40/43,693 Int. Cl. B22d 27/16 US. Cl. 164-255 2Claims ABSTRACT OF THE DISCLOSURE Ingots are cast into the cavity of anopen top metallic mold. The upright mold wall has perforations and islined by a thin permeable sand lining covering the perforations. Anevacuated jacket surrounds the mold and molten metal is supplied to thebottom of the mold cavity.

This invention relates to a method for casting ingots under a gas streamand more particularly relates the casting of ingots of metals or alloys.

In general, steel or cast iron is utilized as mold material when ingotsof metals or alloys are made and the mold has a long useful life.Sometimes a surface crease, crack, surface folding or blow hole iscaused on the surface or in the interior of the ingot because of thehigh heat conductivity of the mold material and the surface lubricantused. Minor faults disappear with increasing reduction during rollingbut serious faults remain after the ingots are processed to finishedgoods. These goods cannot be used.

An object of this invention is to provide a mold for casting ingots ofmetals or alloys with sound interior and sound outer surfaces in which amembrane formed by a thin sand lining is provided on the inner surfaceof a metallic mold to reduce the cooling speed of the surface of theingots so that faults such as surface creases, cracks, surface folds orblow holes are prevented from appearing on the outer surface or in theinterior of the ingots, and the gas generated from the membrane isexhausted outward the metallic mold.

In the prior art, such as shown in Pat. No. 3,099,052, air or an inertgas, e.g. argon, helium or nitrogen etc., is forced through thepermeable material of a mold during casting, the fluid flowing outwardof the mold so that no blow hole occurs.

In the present invention, the gas stream is used in a sand linedmetallic mold with the same effect. Sound ingots having no blow hole, nosurface crease nor crack are obtained in accordance with the presentinvention.

Other objects and advantages of the present invention will becomereadily apparent from the following detailed description of the drawing,in which:

FIGS. 1 and 2 show apparatus for casting ingots according to the presentinvention in respective elevational sections,

FIG. 3 is a similar view of a modified apparatus of the presentinvention,

FIG. 4 is a corresponding view of yet another apparatus of the presentinvention,

FIGS. 5(1) and (2) respectively show the surface condition of a steelingot made in accordance with a conventional method for casting ingotsusing a metallic mold and the surface condition of a stainless steelingot made in accordance with the method for casting ingots of thepresent invention,

FIGS. 6(1) and (2) are graphs showing the roughness of the surfacesillustrated in FIGS. 5(1) and (2), respectively, and

FIG. 7 shows a sectioned steel ingot made in a conventional metallicmold and a sectioned alloy ingot made in accordance with the presentinvention, respectively.

In FIG. 1, a thin, permeable sand lining 3 (shell mold,

-CO mold) is baked to the inner surface of a heavy,

perforated metallic mold 1. The holes in the mold 1 are distributeduniformly and preferably filled with nonillustrated steel wires having amelting point above 1000 C., in order to prevent entry of molten metalinto the holes while permitting gas generated in the mold and a gasstream applied to the mold to be exhausted through the holes. Theoutside of the metallic mold 1 with the sand lining 3 is separated fromthe atmosphere by a vessel 8 closed by a plate member 10 made of paperor metal. The vessel 8 is partly filled with shot 9 and partly keptwithout filler. The bottom of the mold cavity 6 com municates with arunner 2.

The apparatus shown in FIG. 1 is operated in the following manner: whilemolten metal 7 is poured into the mold cavity 6 through the runner 2,the pressure in the vessel 8 is reduced 'by means of a non-illustratedvacuum pump. At the same time, air or an inert gas is introduced througha riser 5 and is exhausted through the sand lining 3 and the holes inthe mold 1. If air or an inert gas, such as argon, helium or nitrogen isintroduced, the gas generated from the sand lining during casting iscarried away by the inert gas without penetrating into the molten metal.No faults due to the gas are found after the molten metal is solidified.

The apparatus of FIG. 2 is similar to the apparatus shown in FIG. 1except for the provision of a hollow metallic mold 11" which combinesthe functions of the mold 1 and of the vessel 8. The operation and theeffect of the appartus shown in FIG. 2 are similar to those of theapparatus shown in FIG. 1.

In FIG. 3, a metallic mold 1, a sand lining 3, a riser 5, a mold cavity6 and a runner 2 are similar to corresponding elements of FIG. 1. Aninert gas is applied to the molten metal in mold cavity 6 from the topof the riser 5 through a pipe 12 under positive pressure. The gasgenerated from the sand lining 3 is driven out of the mold as explainedwith reference to FIG. 1.

In FIG. 4, a thin sand lining 3 is provided on the outer face of ametallic mold 1 surrounded by a vessel 8 equipped with a riser 5. Moltenmetal 7 is fed from a. runner 2 to a mold cavity 6 between the lining 3and the vessel 8 to form a hollow ingot. The mold 1 is exhausted bymeans of a vacuum pump through an exhaust pipe 13 connected thereto andgas is led from the mold cavity 6 to the exhaust pipe 13 through thesand lining 3 and the metallic mold 1. The gas generated from the sandlining 3 is exhausted out of the mold as explained in reference to FIG.1.

The present invention was applied to the casting of ingots as follows:

EXAMPLE 1 An 18-8 stainless steel ingot weighing 9 kg. was cast in acast iron mold of the invention which had a diameter of mm. and a heightof mm. The mold had 30 holes of 20 mm. diameter which were filled withsintered iron. The lining of the mold consisted of silica sand bondedwith phenolic resin and was 6 mm. thick. Air was drawn into the mold ata rate of 1.2 liters per minute per cm. by a vacuum of mm. water columnin the mold.

FIG. 5(1) shows the surface of the ingot so produced. FIG. 5(2)similarly shows the surface of an ingot of the same metal cast in aconventional metal mold.

As is shown in FIG. 6, the average surface roughness measured by acontact-point type instrument was 132p maximum for the conventionalingot 1 and was 33a maximum for the ingot 2 of the invention.

3 EXAMPLE 2 A pure nickel ingot was prepared by the present inventionunder the following condition:

The cast iron mold employed had dimensions of 230 mm. x 100 mm. x 575mm., and had 70 holes 50 mm. in diameter filled with sintered iron. Thesand lining was 5 mm. thick, and air was drawn into the mold at a rateof liters per minute per cm. by a negative pressure of -150 mm. watercolumn. The ingot weighed 100 kg.

Faults due to secondary shrinkage occurring at rolling were eliminatedby the method of the present invention.

Sections of the ingots obtained by the method of the invention (rightside) under the conditions stated above and by a conventional method(left side) are shown in FIG. 7.

EXAMPLE 3 An ingot used as raw material for 18-8 stainless steel pipewas prepared in a cast iron mold, 516 mm. X 516 mm. x 1500 mm. providedwith 196 holes 86 mm. in diameter and filled with steel wire. The moldwas lined with 10 mm. of chromite sand bonded with phenolic resin, andair was drawn into the mold at a flow rate of 1.6 liters per minute percm. by a negative pressure of 200 mm. water column in the mold, Theingot weighed 3000 kg.

Suitable lining materials include silica sand, zircon sand, chromitesand, alumina, magnesia or mixtures thereof.

The binder for the lining may be a synthetic resin, another organicmaterial or an inorganic material. Suitable synthetic resins includephenol resin, furan resin, urea resin, polyvinyl alcohol, etc., theother organic material may be a drying oil cereal, or sodium alginate,and said inorganic material may be clay, sodium silicate, ethylsilicate, silicic acid gel etc.

As shown in the following table, the time for finishing the surface ofingots cast by the present invention is reduced to A of that needed witha conventional casting method and the yield for finished ingots isimproved by TAB LE Conven- Method of tional present method inventionTime for preparing surface of ingots in hours... 3. 0 0. 3 Yield forfinished ingots in percent 86. 5 95. 0

What we claim is: 1. An apparatus for casting ingots comprising:

(a) a unitary self-sustaining metallic mold member having an outerupright face and .an inner upright face, said mold member being formedwith a plurality of openings therethrough between said faces, said innerface bounding a mold cavity having an open top and communicating withthe atmosphere through said top;

(b) a permeable sand lining covering said inner face and said openings,the thickness of said sand lining being much smaller than the thicknessof said mold member between said faces thereof;

(c) a vessel enveloping said outer face and defining a substantiallyclosed space with said outer face;

(d) means for evacuating said space and for thereby drawing a gas streamfrom said mold cavity through said lining and said openings; and

(e) supply means other than'said' open top for supplying molten metal toa portion of said mold cavity below said openings.

2. An apparatus as set forth in claim 1, wherein said supply meansinclude a runner having an orifice in said cavity below said openings.

References Cited UNITED STATES PATENTS 315,741 4/1885 Henderson 164-1203,006,046 10/ 1961 Shephard et al. 164-16 3,098,268 7/1963 Zifferer164-16 3,099,868 8/1963 Grott 164-16 3,099,052 7/1963 Suzuki et al.164-66 3,222,735 12/1965 Sylvester 164-306 X 2,991,267 7/1961 Bean260-38 863,733 8/1907 Lustig 164-66 3,210,810 10/1965 Potter 164-12 X1,544,592 7/1925 Murray 249-114 X 2,997,756 8/196-1 Strom 164-255 X2,379,401 6/1945 Poulter 164-255 X 2,489,322 11/1949 Olsen et al 249-141X 783,576 2/1905 Haggenjos 164-410 1,855,529 4/1932 Poe 249-1141,585,391 5/1926 Kubota 249-114 X 2,312,796 3/ 1943 Campbell 164-255 I.SPENCER OVERHOLSER, Primary Examiner V. RISING, Assistant Examiner US.Cl. X.R.

